Method for controlling a printer or copier using a toner mark band and reflex sensor working according to the triangulation principle

ABSTRACT

A method and device controls a printer or copier to generate a plurality of marks that are assembled into a coherent marking band that is then inked by the toner. A sensor measures the marking band. The printer or copier are controlled based on the output of the sensor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a method to control a printer or copier, in thatmarking data for toner markings for a character generator are stored inan image control, and in that the character generator generates in anintermediate carrier a latent image corresponding to the marking datathat is inked with toner material in the further course, whereby tonermarks are generated on the intermediate carrier. Furthermore, theinvention concerns a device to implement this method.

Furthermore, the invention concerns a method to control a printer orcopier using an optical reflex sensor, as well as a device for this.

2. Description of the Related Art

In order to print a print image on a print medium (for example paper)with consistent inking, a permanent monitoring and regulation of theelectrophotographic or electromagnetic processes is necessary. For thismonitoring and regulation, different toner marks adapted to therespective processes are applied to the intermediate carrier (that is,for example, an organic photoconductor band, also called an OPC band(OPC organic photoconductor)) or to a transfer band; these toner marksare scanned with the aid of sensors and the results used to control theprint process. For example, the blackening of the toner mark can bemeasured with the aid of a reflex sensor. Another possibility is todetect the toner layer thickness with the aid of a capacitive layerthickness sensor. Another method utilizes the electric toner charge,whereby the charge potential is measured with the aid of a potentialsensor. The problem exists in these procedures to apply differentmarkings to the intermediate carrier independent of the print image tobe printed and independent of a temporal control, and to synchronizethese toner markings with the evaluation by the sensor or sensors.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a method and a device withwhose help a control of the print processes can be implemented in asimple manner and given different print processes, under evaluation ofthe toner markings.

An electrophotographic printing device is known from PCT PublishedApplication WO 00/34831 by the same applicant in which two printingunits print images onto a transfer band that transfers these images inthe further course to a carrier material (for example paper). With theaid of a character generator associated with the first printing unit, amarking is printed on the transfer band by the first printing unit atthe beginning of each image. Using this marking, the run time for theimage from its generation can be precisely determined.

It is known from European Patent Document EP-A-0 291 738 to print tonermarkings according to a type of a cross on both sides of images. Withthe aid of these markings, a lateral shifting of the images with regardto the band carrying the images can be determined.

U.S. Pat. No. 5,995,802 specifies a printing device in which a pluralityof printing units are arranged and print images on a transfer band withdifferent colors for a 4-color print. A plurality of markings pertainingto the primary colors black, yellow, magenta and cyan are printedoutside of the actual print region and have been evaluated for theprocess control.

This object is achieved for a method to control a printer or copier, inthat marking data for toner markings for a character generator arestored in an image control; the character generator generates on anintermediate carrier a latent image corresponding to the marking datathat is inked with toner material in the further course; a plurality ofmarkings are combined in the image control into a coherent marking band,whereby each marking has a spatially defined position within the markingband on the intermediate carrier; and that the inked toner markings ofthe marking band are scanned by at least one sensor whose signal is usedto control the print process.

According to the invention, a plurality of markings that are necessaryfor the different electrophotographic or electromagnetic print processesare deposited in a marking band. Accordingly, only one or more markingbands must be accessed for the various electrophotographic orelectromagnetic processes of a device type, and the character generatormust be correspondingly controlled in order to print the necessary tonermarkings. In this manner, the technical expenditure is minimized and thehandling with toner markings is standardized.

A further aspect of the invention concerns the evaluation of the tonermarkings by means of a sensor system. As already addressed furtherabove, given a print process in an electrophotographic orelectromagnetic printer or copier, the color density of inked surfaces,achieved with the aid of toner, depends on a plurality of processparameters. A substantial influence comes from the thickness of thetoner coating achieved during the image development on the intermediatecarrier (for example the photoconductor), which itself in turn candepend on a plurality of further process parameters such as, forexample, the specific surface charge of the toner or the potentialdifference between the photoconductor surface and the surface of a donorelement. For a qualitative high-grade print image, the print processmust be able to maintain the optical density within narrow limits over arelatively long period of time. For this purpose, in manyelectrophotographic printers one or more toner markings are generated onthe intermediate carrier at regular temporal intervals, for the mostpart in a region that is normally not transfer printed. These tonermarkings are then recorded by sensors and evaluated in order toinfluence, for example, the important operating quantities of theaverage toner mass allocation with regard to the surface.

For evaluation of toner markings, it is general prior art to useoptoelectronic reflex sensors that radiate radiation on to surface ofthe toner marking to be measured and that absorb and evaluate radiationreflected from this toner marking surface, as well as from theintermediate carrier surface (for example the surface of thephotoconductor) lying beneath it. This measurement principle enables asufficiently high precision, as long as the following requirements aremet: the toner markings form no closed, opaque toner layer, but rathercomprise punctiform, permeable locations, for example holes; the colorof the toner offers, in the wavelength range of the reflex sensor, asufficiently strong contrast to color and/or brightness of the surfaceof the intermediate carrier; the reflection properties of the surface ofthe intermediate carrier are uniform and temporally unchanging. Givenvery high optical densities on the print substrate or carrier material,the toner layer is opaque for the reflex sensor; this means that areliable conclusion about the actual mass allocation with toner materialis impossible.

Furthermore, the principle of capacitive measurement value detection isknown that detects the change of the dielectric between capacitorelectrodes given a pass through a toner marking. This sensor principlerequires a significant circuitry and signal processing effort in orderto reliably detect capacitance changes in the femto-Farad range. Changesor, respectively, fluctuations of the dielectric properties of the tonermaterial or, respectively, of the intermediate carrier (for example thephotoconductor) must be compensated with the aid of calibrationprocedures.

According to the further aspect of the invention, a method to control aprinter or copier is specified in which an optical reflex sensor thatdetermines the thickness of the toner layer of the toner markingaccording to the triangulation method is used as a sensor to scan therespective toner marking, whereby the print process is controlleddependent on the determined thickness of the toner layer.

In the invention, the toner mass coating with regard to the surface canbe directly inferred from the thickness of the toner marking. This masscoating is a direct input quantity to control the various parameters ofthe print process. In this manner, the quality of the print process canbe further improved. Given the inventive method, very thick andoptically opaque toner layers can thus also be evaluated.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the various aspects of the invention areexplained in the following using the drawing.

FIG. 1 is a schematic diagram showing the principle assembly of aprinter that can print print images on both sides of a carrier material,

FIG. 2 is a schematic diagram showing marking bands and print images inwhich the beginning of the first marking band is synchronized with thebeginning of the first print side,

FIG. 3 is a schematic diagram marking bands and print images in whicheach marking band is synchronized with the beginning of each print side,

FIG. 4 is a functional block diagram with various function units,whereby the data for the various marking bands are asynchronously addedin the transfer of the print data to the character generator.

FIG. 5 is a functional block diagram with various function units,whereby the data for the various marking bands are asynchronously orsynchronously added to the print image before the rastering in thecontroller,

FIG. 6 is a functional block diagram with various function units)whereby the markings are read with the aid of different sensors,

FIG. 7 is a schematic diagram showing the principle assembly of a reflexsensor applying the triangulation principle,

FIG. 8 is a schematic diagram showing the principle assembly of thereflex sensor using micro-optical components, and

FIG. 9 is a schematic diagram showing an assembly of a reflex sensorusing an individual detector with a swing mirror.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a printer that operates according to theelectrophotographic printing principle. A carrier material 10, forexample a paper web, is simultaneously printed double-sided. An uppercharacter generator 14 a generates a latent image on an upperphotoconductor band (also called an OPC band). The character generator14 a also generates the toner marking bands with the toner markings. Apotential sensor 16 a detects the charge potential of the band and ofthe latent image and the band; its signal is further used for processcontrol. An upper developer station 18 a inks the latent image with theprint images and the toner markings with toner material. Viewed in therunning direction of the photoconductor band 12 a, a toner markingsensor 20 a that evaluates the toner markings is downstream after thedeveloper station 18 a. The toner image applied to the photoconductorband 12 a is transferred to an upper transfer band 22 a, and from theretransfer printed on the top of the carrier material 10.

The bottom of the carrier material 10 is printed in a similar manner,wherefore the similarly assembled and similarly arranged function units(namely lower photoconductor band 12 b, lower character generator 14 b,lower potential detector 16 b, lower developer station 18 b, lower tonermarking sensor 20 b and lower transfer band 22 b) are used. The carriermaterial 10, thus printed simultaneously and on both sides, issimultaneously fixed on top and bottom and output in a fixing station24. The shown assembly of the upper printing unit and the lower printingunit is suitable to print a plurality of color separations. For this,the respective transfer band 22 a, 22 b assembles a plurality of tonerlayers of different colors of a print image one atop the other, and thenprints this on the carrier material 10. The following describe examplesof toner bands, their evaluation and the varying device-technicalassembly can be used for the printer shown in FIG. 1.

FIG. 2 shows the assembly of marking bands 30 through 40 that belong tothe print images 42 through 48. A plurality of toner markings iscomprised in each marking band 30 through 40. Each marking has aspatially defined position within the marking band 30 through 40. Themarking bands 30 through 40 are applied to the intermediate carrier in aregion that typically lies outside of the print image to be printed, forexample along an edge track. In this manner, the print images 42 through48 are not disturbed. Alternatively, it is possible to apply the markingbands to the intermediate carrier in a region that lies within the printimage to be printed. It is thereby possible to be able to execute testfunctions and compensation functions in the setup and test run of theprinter.

In the example according to FIG. 2, in every print start the beginningof the first marking band 30 is synchronized with the beginning of thefirst print side 42. The following marking bands 32 through 40 are thenattached together without interval, meaning only the first marking bandis synchronized to the first print side 42; all other marking bands 32through 40 are asynchronous to the further print sides 44 through 48.The advantage of this arrangement is that the length of the respectivemarking band can be independent of the length of the print sides;expressed differently, the length of the marking bands 30 through 40 canbe selected arbitrarily long, independent of form. In such a case, theform lengths can be different and arbitrarily long. The form length hasno influence on the required process regulation that is undertaken withthe aid of the toner markings of the marking bands 30 through 40. Whatis disadvantageous in this version is that the device control mustadministrate every beginning of the individual marking bands 30 through40 dependent on the print sides 42 through 48.

FIG. 3 shows another variant in which the marking bands 30 through 38are respectively synchronized with the beginning of every print side 42through 50. It is hereby advantageous that the beginning of a respectivemarking band 30 through 38 and the beginning of a respective print image42 through 50 can be triggered together. It can be disadvantageous thatthe length of the respective marking band 0 through 38 can maximally bethe length of the respective print image 42 through 50; a limitationdependent on the length of the print image thus exists for the markingbands. Given very long forms, it can ensue that the length of theassociated marking band is very short with regard to the length of theform, such that a precise regulation of the electrophotogaphic processover the large length of the print image is not ensured. A solution forthis problem proposes that a plurality marking bands be added withinsuch a long print side, such that the maximum separation betweensuccessive marking bands is not too great, for example not greater thanapproximately 50 cm (20 inches).

FIG. 4 shows a block diagram with various function units. The charactergenerator (for example the character generator 14 a or 14 b according toFIG. 1) receives data from control units for the print images and forthe marking bands. A controller 52 accesses a marking band storage 54 inwhich data are stored about the marking bands, and a page storage 56 inwhich the data for the print images of the print pages are stored. Therastering of the data ensues individually in the controller for eachpage and for the marking band, i.e. one bitmap is created for the printside and one bitmap is created for the marking band. The controller 52transfers the data of the bitmap to a conversion unit 58 in which thebitmap data of the page storage 56 and the data of the marking bandstorage 54 are combined (indicated by an addition block 60). The data ofthe marking bands are thus added in the transfer of the print data tothe character generator 14 a, 14 b. A device control 62 controls anelectronic screen 64, such that, process-specifically from the markingbands, the necessary toner markings are connected through in data form;the other toner markings are filtered out. In this manner marking bandscan be arbitrarily changed without print sides being changed. Given arestart of the print operation after a stop, in this variant only thedata of the marking band must be newly rastered; the bitmap data of therespective print side remain unchanged. In this manner, the processingspeed upon creation of the bitmap in the controller 52 is increased.

FIG. 5 shows another variant in which identical parts are designatedidentically. Before the rastering in the controller 52, in which (asexpected) a bitmap of the pixel to be printed is generated, the data ofthe various marking bands are asynchronously or synchronously linked tothe data of the respective print image.

It is hereby to be noted that, given the linking thereto of the markingbands in the center track, the print image of the original side iserased in the track area, whereby toner markings and print image of theoriginal side are not mixed. In the arrangement according to FIG. 5, theprint side must also be newly rastered given each change of the markingband.

The electronic screen 64 has, as noted, the objective to filter outunnecessary toner markings in the toner bands. This is necessary so thatsuch unnecessary toner markings are not transferred to the carriermaterial, because they would then have to be completely removed (meaningpurged) by a subsequent cleaning station. Such a purging is, however,elaborate and not absolutely reliable. It is therefore important to onlywrite the actually necessary toner markings in the edge track.

The toner markings on the photoconductor band 12 a, 12 b are evaluatedwith the aid of sensors. FIG. 6 shows the use of three different sensors66, 68, and 70. Since the different toner markings must be firmlyassociated with these various sensors 66, 68, and 70, it must also beassured that each sensor measures only the toner marking specific to it.To synchronize the writing of the toner marking and the reading of thetoner marking, a trigger pulse is generated by the device control forthe sensors 66, 68, and 70 via the line 72 at every beginning of therespective marking band. At the start of the writing of the respectivetoner marking, the time offset to the trigger pulse on the line 72 isstored by the device control 62 and communicated to the respectivesensor 66, 68, and 70 that should evaluate this marking. Since thedevice control knows at every point in time the location of therespective marking band, and the location of the toner marking thereinwith regard to the respective sensor 66, 68, and 70, it can communicateto each sensor 66, 68, and 70 the point in time of the passage of therespective marking. Each sensor 66, 68, and 70 can hereby evaluate aplurality of toner markings in succession.

Numerous variants of the specified exemplary embodiments according toFIGS. 1 through 6 are possible. For example, it is possible to evaluatewith the aid of sensors toner markings that are printed on the transferband 22 a, and 22 b. Furthermore, marking data can be stored for aplurality of toner markings; a marking band or a plurality of markingbands can then be assembled from this plurality of toner markings,whereby an associated marking band is selected dependent on the selectedprint process. In this manner, all toner markings can be prepared fordifferent types of a device type and combined into marking bands. Withthe aid of the electronic screen, it is then possible to select theactual required toner markings on the marking bands.

In a further alternative, a single marking band is defined whose tonermarkings permit the plurality of print processes of a device type tocontrol the printer or copier. This measure serves for the unificationand the simpler software-technical handling with the toner markings.

In the exemplary embodiment according to FIG. 1, two printing units withrespectively one transfer band are provided within a single device,whereby the upper transfer band 22 a provides the top of the carriermaterial 10 with a toner image, and the lower transfer band 22 blikewise provides the bottom of the carrier material with a toner image.Marking bands with toner markings are applied to each transfer band.According to a development, the application of the marking bands on bothof the transfer bands 22 a, and 22 b ensues such that two toner markingsinked with toner are not simultaneously juxtaposed at the commontransfer printing location for both transfer bands 22 a, and 22 b. Inthis manner, the problem of the creation of toner dust is avoided. Thetoner markings of the toner bands namely lie in the edge track outsideof the carrier material. If the toner marking of the upper transfer bandand the toner marking of lower transfer band were to now come in contactin this edge zone, due to a lack of paper in this region, toner dustwould thus ensue. The cited development prevents this problem.

A further problem can ensue if the same toner marking were always to bewritten at the same location of the photoconductor band. This can leadto a memory effect in the photoconductor band and change the inking ofthe toner marking. Therefore) in a development of the invention it isensured that the length of the respective marking band is not a multipleof the length of the photoconductor band.

FIG. 7 shows in a principle view an optical reflex sensor to scan thetoner marking, as can for example be used as a toner marking sensor 20a, and 20 b according to FIG. 1. The reflex sensor comprises as aradiation source a laser diode 80 whose radiation is concentrated into ascanning beam 84 by a collimator lens 82. The laser diode 80 radiatesmonochromatic radiation, for example in the range of the near-infrared.However, other wavelength ranges of the radiation can also be used.

The scanning beam 84, which is arranged to be incident on the carrier ina substantially perpendicular direction, impinges on the respectivesurface in the passage of the intermediate carrier 86 with the tonermarking 88. It is shown in FIG. 7 that the scanning beam 84 impingeshalf on the surface of the toner marking 88 and half on the surface ofthe intermediate carrier 86 (for example a photoconductor band) andthere respectively generates a measurement spot 90 or, respectively, 92.The measurement spots 90, and 92 are typically smaller than 1 mm². Theradiation is diffusely reflected in a substantial part by the respectivemeasurement spot 90, and 92. Imaging optics 96 (for example a convexlens) bounded by a screen 94 image the measurement spots 90, and 92 on alinear detector array 98 as measurement spot 90′, and 92′. The imagingradiation beam of the measurement spot 90 is indicated in FIG. 7 with adash-dot pattern and has the reference number 100. The radiation beamoriginating from and imaging the measurement spot 92 is indicated dashedin FIG. 7 and has the reference number 102.

The measurement spots 90, and 92 have a perpendicular separation H fromone another, corresponding to the thickness of the toner marking 88. Theimaged measurement spots 90′ and 92′ have a separation D from oneanother. The quantities H and D stand in an exact proportion defined bythe geometry of the optical beam path. The height H, and therewith thethickness of the toner marking 88, can clearly be inferred back from theseparation D. The angles 104 and 106 between the scanning beam 84 andthe respective middle rays of the radiation beams 100, and 102 also gointo the calculation.

The linear detector array 98 transduces the striking radiation intoelectrical voltages that are processed by a digital signal processor 108in the form of signal curves. For more precise determination of thepositions of the measurement spots 90, and 92 or, respectively, theimaged measurement spots 90′ and 92′, the center of area of the signalcurves over the measurement spots 90′, and 92′ can be determined. Theseparation of these centers of area then leads to the quantity D, andtherewith indirectly to the quantity H. The determination of theseparation H from the separation D of the measurement spots 90′, and 92′under consideration of the beam geometry is also designated as atriangulation method. Instead of the mentioned determination of thecenter, other calculation rules can also be used that yield a clearconnection between the quantities D and H. Furthermore, it is possibleto determine the quantity H from the quantity D with the aid of acalibration method, without precise knowledge of the beam geometry.Moreover, it is possible to achieve a higher precision with the aid ofaveraging over a plurality of focal spots along the toner marking 88 orthe surface of the intermediate carrier 86.

The mass coating with regard to the area can be determined (in grams perareal unit) via calibration from the thickness H of the toner layer ofthe toner marking 88. Such a quantity is particularly well-suited tocontrol the print process.

The signal processor 108 forwards the quantities determined by it to thedevice control for the printer or copier via the line 110. The laserdiode 80 (whose output power is typically in the range of 1 mW) iscontrolled by the signal processor 108 via a controllable power source111. The current supplied to the laser diode 80 can be measured suchthat the signal at the detector array 98 lies within a predeterminedrange. In this manner, an undercontrol and overcontrol can be avoided.Furthermore, the current for the laser diode 80 can be adjusted suchthat the signal on the side of the detector array 88 remains constant,independent of reflection capability of the toner marking 88 or of thesurface of the intermediate carrier 86. Via this measure, the sensorarrangement is independent of the reflection capability of the tonermarking 88 or, respectively, the intermediate carrier 86, whereby thesignal-to-noise ratio is improved given a scanning of high-contrastsurfaces.

To suppress interfering light, a color filter 113 can be connected infront of the detector array 98, preferably a bandpass filter, which isadapted to the wavelength of the radiation of the laser diode 80.Extraneous light is thus filtered out.

FIG. 8 shows a further exemplary embodiment of the reflex sensor;identical parts are designated identically. As imaging optics 96, aplanar, strip-shaped Fresnel lens is provided that guides the diffuselight originating from the measurement spot to the detector 98 via amicroprism 112. The microprism 112 deflects the radiation by 90′. Thecomponents Fresnel lens and microprism can be economically produced viacasting technique. The assembly can be significantly shrunk andsimplified with the arrangement shown in FIG. 8.

FIG. 9 shows a further exemplary embodiment of the reflex sensor,whereby a single detector 1114 (for example a detector that operatesaccording to CMOS technology) is used as a radiation receiver. Forreasons of overall size, a Fresnel lens is once again used as theimaging optics 96. The radiation is supplied to the individual detector114 via a controllable swing mirror 116. This swing mirror is applied toan electrically-conductive substrate with the electrodes 118 and iselastically suspended via torsion springs 120. Via the application of analternating voltage to the electrodes 118, the swing mirror 116 isdisplaced according to the arrow 122 in periodic oscillations ofconstant amplitude. The light impinging on the individual detector 114therefore has a temporal modulation also corresponding to the electricalsignal delivered by it. The time curve of the brightness, and therewiththe curve of the measurement spot over the imaging location, is alsocomprised in this signal, from which the height of the toner marking 88can be inferred. Another variation provides that the voltage at theelectrodes 118 is regulated such that the individual detector 114 alwaysreceives the maximum light density of the light guided to it. In thiscase, the electrode voltages are a measure for the position of therespective measurement spot. As a further alternative, a piezoelectricor an electromagnetic converter can be used as an actuator for the swingmirror 116.

The specified measurement principle is used in connection with thescanning of toner markings on an intermediate carrier 86 that isgenerally fashioned as a photoconductor, for example as a photoconductorband. Such a photoconductor band as a rule requires a certain relaxationtime after the exposure with an intensive radiation source, so that adefinite discharge state appears given successive exposure events. Ifthis relaxation time is too short, a memory effect appears, meaning theeffect of a plurality of successive exposure events partially adds up,and the photoconductive surface is more deeply discharged than isdesired. This memory effect impairs the precision of the measurementeffect at the toner marking. To prevent this memory effect, threepossibilities are subsequently presented.

A first possibility provides to attenuate or to interrupt the scanningbeam. For this, the power supply for the radiation source (for examplethe laser diode 80) can be connected and disconnected. Another variantis the interruption of the scanning beam 84 with the aid of a mechanicaldiaphragm, for example by a rotating diaphragm. Another possibility tointerrupt the scanning beam 84 is the use of an electro-optical liquidcrystal shutter that is switched from a transparent state to a diffusestate upon the application of an electrical voltage, such that thescanning beam 84 is significantly, diffusely scattered, and notightly-focused measurement spot impinges on the surface of thephotoconductor 86. Thus, no measurable discharge of the photoconductorensues. Such an arrangement requires no moving parts and ensures shortreaction times in the range of less than a millisecond.

A second possibility to prevent the memory effect is the positionvariation of the toner markings. Toner markings are hereby used thathave a multiple of the required width of the scanning beam. The scanningbeam can then be displaced in its position from rotation to rotation ofthe photoconductor, for example by at least one track width, such thatthe relaxation time for the exposed track is extended. The displacementof the scanning beam can, for example, ensue via a mechanical shiftingof the sensor head or, respectively, of the radiation source. Anotherpossibility is the rotation of the sensor head or, respectively, of theradiation source around an axis, parallel to the scanning beam 84, thatlies outside of the beam axis. A further possibility is the selection ofoptical means, for example mirrors or prisms, that are movedmechanically.

A third possibility to prevent the memory effect lies in the selectionof a wavelength of the radiation for the radiation source for which thephotoconductor is not sensitive. When, for example, the photoconductoris sensitive in the long-wave radiation range and insensitive in theshort-wave radiation range, no memory effect can be caused given the useof a radiation source with short-wave radiation. Particularly suited asradiation receivers are CCD detectors that, due to their wide-bandsensitivity, are appropriate to register radiation in the visible and inthe near-infrared range.

The reflex sensor specified in the preceding Figures is suitable todetermine both partially-transparent and opaque toner layers of a tonermarking of different colors on a background with approximately arbitrarycolor and reflection property. Due to a thickness measurement, theimportant quantity for the mass coating of the toner can also bedetermined.

The specified reflex sensor can be modified in many cases. For example,beam sources with different wavelengths can also be used, whereby anadaptation to the reflection property of the respectively used toner canensue. For example, the light from two discrete laser diodes coupled ina common beam path can also be used to generate the radiation with twodifferent wavelengths. A semi-permeable mirror is preferably used forthis. Given appropriate selection of the wavelengths, the brightnessdistribution forms two geometric clearly separate brightness maxima onthe detector array when the measurement spot scans the edge of the tonermarking. The geometric separation of the brightness maxima on thedetector array is a measure of the height of the step between theintermediate carrier and the toner marking surface. Also, rastered tonermarkings can also advantageously be used whose raster width is smallerthan the radius of the scanning beam. Two brightness maxima always thenarise on the detector when the scanning beam scans the rastered tonermarking.

In place of a conventional laser diode with band-shaped light emissionand elaborate collimator optics, a vertically emitting laser diode canadvantageously be used, what is known as a VCSEL component (VCSEL standsfor vertical cavity surface emitting laser diode). The lesser divergenceangle and the approximately circular beam cross-section of the VCSELcomponent requires no or only very simple optical elements for beamshaping.

The specified reflex sensor can be integrated in a simple manner into aCAN network, as this is necessary for controlling more complexelectrophotographic printing machines that use networked processormodules over a field bus system. The signal processor 108 thenadvantageously comprises a corresponding interface to connect to the CANnetwork.

The specified reflex sensor can also use toner coatings for contrastmeasurement. For this, given a given exposure strength a cumulativevalue of the light impinging on the detector array is calculated. Inthis manner, for example, weakly-reflecting toner coatings can bedetected, and these can be utilized to control the print process.

Although other modifications and changes may be suggested by thoseskilled in the art, it is the intention of the inventors to embodywithin the patent warranted hereon all changes and modifications asreasonably and properly come within the scope of their contribution tothe art

1. A method to control a print or copier, comprising the steps of:storing marking data for toner markings for a character generator in animage control; generating a latent image on an intermediate carrierusing the character generator corresponding to the marking data;combining a plurality of markings in the image control into a coherentmarking band, each marking having a spatially defined position withinthe marking band on the intermediate carrier; inking the marking bandwith toner material; scanning the toner markings of the marking band byat least one sensor; controlling a print process using a signal of theat least one sensor; storing measurement data for a plurality of tonermarkings; assembling at least one marking band from the plurality oftoner markings; and selecting an appropriate marking band dependent on aselected print process.
 2. A method according to claim 1, furthercomprising the step of: defining a single marking band whose tonermarkings permit a plurality of print processes of a device type tocontrol a printer or copier.
 3. A method according to claim 1, furthercomprising the step of: applying the at least one marking band with theplurality of toner markings to the intermediate carrier in a region thatlies within a print image to be printed in order to be able to implementtest functions and compensation functions.
 4. A method according toclaim 1, further comprising the step of: applying the at least onemarking band to the intermediate carrier along an edge track outside ofa print image to be printed in order to not disturb the print image. 5.A method according to claim 1, further comprising the step of:synchronizing a beginning of the at least one marking band with abeginning of a print side after each print start, a beginning of themarking band coinciding with a beginning of a print side.
 6. A methodaccording to claim 1, wherein said at least one marking band comprises aplurality of marking bands, and further comprising the step of:controlling beginnings of successive ones of said plurality of markingbands by the image control independent of pages to be printed.
 7. Amethod according to claim 6, further comprising the steps of;synchronizing each of said plurality of marking bands with a beginningof each print side, a beginning of a respective marking band coincideswith a beginning of a respective print side.
 8. A method according toclaim 1, wherein said at least one marking band comprises a plurality ofmarking bands, and further comprising the steps of: serially connectingsaid plurality of marking bands given a greater page length of a printside.
 9. A method according to claim 1, further comprising the step of:combining data for print sides and data for marking bands in a transferof data to the character generator.
 10. A method according to claim 1,further comprising the step of: combining data of the marking bands anddata for the print sides in the image control before generation of imageraster data.
 11. A method according to claim 1, wherein an electronicdiaphragm control acts on the character generator such that thecharacter generator only generates latent images on the intermediatecarrier for predetermined toner markings of a marking band.
 12. A methodaccording to claim 11, further comprising the step of: selecting tonermarkings by a device control depending on a selected print process. 13.A method according to claim 1, further comprising the steps of:providing a plurality of scanning sensors to scan toner markings;signaling a beginning of a marking band via a trigger pulse using adevice control; and actively switching respective ones of said pluralityof scanning sensors with regard to this trigger pulse to scanpredetermined toner markings.
 14. A method according to claim 1,providing a band shaped intermediate carrier as said intermediatecarrier.
 15. A method as claimed in claim 14, wherein said intermediatecarrier band is an organic photoconductor (OPC) band.
 16. A methodaccording to claim 1, further comprising the steps of: providing twoprinting units within a device, each of said two printing units havingone respective intermediate carrier band; providing a top of a carriermaterial with a toner image using an intermediate carrier band;providing a bottom of the carrier material with a toner image using theother intermediate carrier band; and applying marking bands with tonermarkings to each intermediate carrier band.
 17. A method according toclaim 16, wherein said step of applying the marking bands on bothintermediate carrier bands ensues such that two toner markings inkedwith toner are not simultaneously juxtaposed at the common transferprinting location for both transfer bands.
 18. A method according toclaim 1, further comprising the step of: selecting a length of themarking band such that it is not an even-number multiple of a length ofthe intermediate carrier.
 19. A method according to claim 1, furthercomprising the steps of: determining a thickness of a toner layer of thetoner marking according to a triangulation method using an opticalreflex sensor as a sensor to scan respective toner marking; andcontrolling the print process dependent on a determined thickness of thetoner layer.
 20. A method according to claim 19, wherein said opticalreflex sensor includes: at least one laser diode that radiates radiationin a direction of the toner marking as a radiation source; and one of alinear detector array and a two-dimensional detector array as areceiver.
 21. A method according to claim 20, further comprising thesteps of: generating at least one measurement spot using at least onelaser diode; and imaging said at least one measuring spot on said one ofsaid linear detector array and said two-dimensional detector array via alens.
 22. A method according to claim 21, further comprising the stepsof: determining a curve of brightness along the respective measurementspot for each measurement spot; and determining a center of therespective measurement spot dependent on the curve; and determining athickness of the toner layer dependent on the separation between thecenters of the measurement spots.
 23. A method according to claim 22,further comprising the step of: using a balance point of the curve ofthe brightness as a center for the respective measurement spot.
 24. Amethod according to claim 21, further comprising the step of: varying aposition of said at least one measurement spot on the toner marking fromrotation to rotation of the intermediate carrier.
 25. A method accordingto claim 20, further comprising the step of: using a controlled powersupply for the laser diode; and measuring supplied current such that thesignal of said one of said linear detector array and saidtwo-dimensional detector array lies within a predetermined range.
 26. Amethod according to claim 20, further comprising the step of: adjustingcurrent for the laser diode such that a signal on a side of the receiverremains constant and independent of the reflection property of at leastone of toner marking and the intermediate carrier.
 27. A method asclaimed in claim 26, wherein said intermediate carrier is aphotoconductor surface.
 28. A method according to claim 20, wherein abeam emitted by the laser diode is one of attenuated and interrupted.29. A method according to claim 28, further comprising the step of:interrupting the beam using a mechanical diaphragm.
 30. A methodaccording to claim 28, further comprising the step of: interrupting thebeam using a voltage-controlled liquid crystal shutter.
 31. A methodaccording to claim 19, further comprising the step of: determining amass coating with regard to area is determined from the thickness of thetoner layer via calibration.
 32. A method as claimed in claim 31,wherein said determining step determines the mass coating in grams perunit area of the toner.
 33. A method according to claim 19, wherein saidreflex sensor includes a color filter on a receiver side via whichextraneous light is suppressed.
 34. A method as claimed in claim 33,wherein said color filter is a bandpass filter.
 35. A method accordingto claim 19, further comprising the step of: using a radiation source asthe reflex sensor having a radiation wavelength outside of a sensitivityrange for the wavelength of the light of said intermediate carrier. 36.A method according to claim 19, wherein said radiation source of thereflex sensor radiates radiation with two different wavelengths.
 37. Amethod according to claim 36, further comprising the steps of: couplingthe radiation of two laser diodes in a mutual beam path to generate theradiation of different wavelengths.
 38. A method as claimed in claim 37,wherein said step of coupling uses semi-permeable mirrors.
 39. A methodaccording to claim 19, further comprising the step of: using a verticalcavity surface emitting laser diode (VCSEL) radiation source as aradiation source.
 40. A method according to claim 19, further comprisingthe step of: using an individual radiation receiver on the receiver sideto which radiation is supplied via a mirror that can be varied withregard to its angle of rotation.
 41. A device to control a print orcopier, comprising: an intermediate carrier; an image control operableto control storage of marking data for toner markings; a charactergenerator connected to said image control and operable to generate alatent image on said intermediate carrier corresponding to the markingdata; said image control being operable to combine a plurality ofmarkings into a coherent marking band, each marking having a spatiallydefined position within the marking band on the intermediate carrier; aninking apparatus positioned adjacent to said intermediate carrier andoperable to ink the latent image with toner material; at least onesensor operable to scan the toner markings of the marking band andconnected to provide an output signal to control the print process; anda storage in which measurement data are stored for a plurality of tonermarkings; said image control being operable to assemble at least onemarking band from said plurality of toner markings, an appropriatemarking band being selected dependent on a selected print process.
 42. Adevice according to claim 41, wherein a single marking band is definedwhose toner markings permit the plurality of print processes of a devicetype to control a printer or copier.
 43. A device according to claim 41,wherein the at least one marking band with the plurality of tonermarkings is applied to the intermediate carrier in a region that lieswithin the print image to be printed, in order to be able to implementtest functions and compensation functions.
 44. A device according toclaim 41, wherein the at least one marking band is applied to theintermediate carrier along an edge track outside of the print image tobe printed, in order to not disturb the print images.
 45. A deviceaccording to claim 41, wherein a beginning of a first marking band issynchronized with a beginning of a first print side after each printstart, whereby the beginning of the first marking band preferablycoincides with the beginning of the first print side.
 46. A deviceaccording claim 41, wherein the image control administrates thebeginnings of the successive marking bands independent of pages to beprinted.
 47. A device according to claim 46, wherein each marking bandis synchronized with the beginning of each print side, whereby thebeginning of the respective marking band preferably coincides with thebeginning of the respective print side.
 48. A device according to claim41, wherein a plurality of marking bands are connected serially given agreater page length of a print side.
 49. A device according to claim 41,wherein the data for print sides and the data for marking bands arecombined in the transfer of the data to the character generator.
 50. Adevice according to claim 41, wherein the data of marking bands and thedata for print sides are combined in the image control before thegeneration of image raster data.
 51. A device according to claim 41,further comprising: an electronic diaphragm control acts on thecharacter generator such that the character generator only generateslatent images on the intermediate carrier from predetermined tonermarkings of a marking band.
 52. A device according to claim 41, furthercomprising: a plurality of scanning sensors are provided to scan tonermarkings; a device control signals the beginning of a marking band via atrigger pulse; and the respective scanning sensor is actively switchedwith regard to this trigger pulse to scan predetermined toner markings.53. A device according to claim 41, wherein said intermediate carrier isan intermediate carrier band of an organic photoconductor (OPC).
 54. Adevice according to claim 41, further comprising: two printing units,with respectively one intermediate carrier band, are provided within adevice, whereby an intermediate carrier band provides the top of acarrier material with a toner image, and the other intermediate carrierband provides the bottom of the carrier material with a toner image, andin which marking bands with toner markings are applied to eachintermediate carrier band.
 55. A device according to claim 54, in whichthe application of the marking bands on both intermediate carrier bandsensues such that two toner markings inked with toner are notsimultaneously juxtaposed at the common transfer printing location forboth transfer bands.
 56. A device according to claim 41, wherein alength of the marking band is selected such that it is not aneven-number multiple of the length of the intermediate carrier.
 57. Adevice according to claim 41, further comprising: an optical reflexsensor that determines a thickness of a toner layer of the toner markingaccording to the triangulation method is used as a sensor to scan therespective toner marking, and that the print process is controlleddependent on the determined thickness of the toner layer.